"So we can take off easily enough … but if we can't see where we're coming down, we won't do it.

And we want to make sure that aircraft, once they drop [water], have a long, safe exit out so they can go back and get a reload."

In a news conference on Tuesday, Premier Rachel Notley said efforts to control the fire's eastern border "are likely to be more successful today" now that air tankers and helicopters are back in the fight.

"That work is underway," Notely said. "The wind dynamics will determine whether the eastern border can be held later today. Additional evacuation alerts may be necessary as the situation develops."

Notley said there are nine helicopters and 14 air tankers assisting 135 firefighters on the ground in Waterton. Another 125 firefighters and 23 helicopters are on standby.

'They were getting pounded'

Two of the province's eight air tanker groups are assisting in Waterton, Missal said.

Missal and one other air attack officer are supervising 12 pilots, five aircraft maintenance engineers and lots of support staff maintaining a fleet of fixed-wing aircraft and helicopters.

The CL-215 skimmer plane, more commonly known as a water bomber, sits behind the plane Mark Missal calls the "bird dog." The small plane will go out and monitor conditions before either the CL-215 or the L-188 can fly. (Sarah Lawrynuik/CBC)

A smaller plane, which Missal calls "the bird dog," will scout ahead and monitor flying conditions before the larger CL-215 water bombers and L-188 Electra air tankers go to work.

Missal said the Electra can carry a 9,500-litre payload, while the CL-215 can drop more than 4,500 litres in under 12 seconds.

A helicopter takes off to battle the Kenow wildfire, which is spreading through Waterton Lakes National Park. (Sarah Lawrynuik/CBC)

Helicopters equipped with water buckets have been able to fly more than any of the other air resources, but even they've been grounded on and off through the past few days, Missal said.

"I mean, they're very slow, but [wind is] very hard on a helicopter in terms of maintenance. And yes, they were getting pounded pretty good, too."

Missal said some of the pilots on the aerial team travelled from Abbotsford, B.C., to help fight the Kenow fire, while some are captains with major commercial airlines.

"They come back to do this type of work because nobody in the world gets to fly a plane like this," Missal said.

'Mother nature wanted the burn'

Although air tankers don't put out fires, aerial crews work on suppression and supporting firefighters on the ground to "buy them time," Missal said.